There are various existing gas sensors formed with a sensitive film, a physical value of which is changed by adsorption, desorption or the like of a gas, on a substrate. The film is capable of calculating a concentration of the gas by measuring the change in the physical value of the sensitive film. Favorable characteristics of a gas sensor include high sensitivity, excellent selectivity, high response speed, reliability, ease of fabrication, small-size, and low power consumption.
Sensitivity or selectivity of such a gas sensor is significantly dependent on the temperature of the sensitive film, and therefore a heater is provided in the vicinity of the film and the temperature of the film is controlled to a specific temperature (300° C. to 500° C.) by using, for example, a control circuit. However, in order for gas permeability, it is difficult to avoid oxidation of the heater, and it results in measurement error.
Thus, the present invention provides a gas sensor structure and manufacturing method thereof to solve the above issues.